Local dimming is used in a Light Emitting Diode (LED) backlight system that is configured to separately control backlight illumination and dimming for local display regions or blocks of an LCD display. LCD display systems can be configured with full array or edge-lit backlight illumination systems, including configuration of the backlight illumination system to provide local illumination and dimming for local display blocks in a full array, or local display regions or blocks in an edge-lit array. For example, local dimming can be implemented in an LCD display with an LED backlight system configured into local display regions or blocks. The backlight LEDs are positioned so that an LED string illuminates an associated local display regions or blocks. Each LED driver string may have a driver that outputs a separate brightness setting, controlling the illumination of its associated LED string. Local dimming control is used to enable dimming control of each local display regions or blocks independent of dimming control applied to the rest of the display. Hence, for local illumination and dimming, LEDs are positioned so that an LED string illuminates a single local display region or block. Each LED (string) driver can be controlled for a separate brightness setting based on local illumination and dimming control. LED driver Integrated Circuits (ICs) may employ multiple channels and, with various dimming methods and on-chip protections. Such ICs may be somewhat application specific, adapted to provide backlighting control for a particular type of device, such as smartphones, tablet computing devices, notebook computers, computer displays, televisions, or the like.